Differences in plant shade tolerance constitute a major mechanism driving the succession of forest communities in subtropical forests. However, the indirect effects of differences in light requirements on the growth of mid- and late-successional tree species are unclear, and this potential growth effect has not been explained at the transcriptome level. Here, a typical mid-successional dominant tree species, Schima superba Gardn. et Champ, and a typical late-successional dominant tree species, Cryptocarya concinna Hance were used as materials and planted under 100% full light (FL) and 30% FL (low light, LL) to explore the responses of tree species in different successional stages of subtropical forests to different light environments. Transcriptome sequencing was used to analyze the expression changes in genes related to growth and photoprotection under different light environments. The young leaves of S. superba accumulated more malondialdehyde (MDA) and superoxide radicals (⁠|${\mathrm{O}}_2^{{{}^{\bullet}}^{-}}$|⁠) under LL. A lower hormone content (auxin, cytokinin, gibberellin) in the young leaves, a weaker photosynthetic capacity in the mature leaves and significant downregulation of related gene expression were also found under LL, which resulted in the total biomass of S. superba under LL being lower than that under FL. The young leaves of C. concinna had less MDA and |${\mathrm{O}}_2^{{{}^{\bullet}}^{-}}$|⁠, and a higher hormone contents under LL than those under FL. There was no significant difference in photosynthetic capacity between mature leaves in contrasting light environments. Although the biomass of C. concinna under LL was less than that under FL, the height of C. concinna under LL was higher than that under FL, indicating that C. concinna could grow well under the two light environments. Our results describing the acclimatization of light at the physiological, molecular and transcriptome levels are important for a complete understanding of successional mechanisms.

中文翻译：

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两种不同演替阶段亚热带森林树种在转录组和生理水平上耐荫性差异的解释

植物耐荫性的差异是驱动亚热带森林群落演替的主要机制。然而，光照需求差异对中后期树种生长的间接影响尚不清楚，这种潜在的生长影响尚未在转录组水平上得到解释。在这里，一个典型的中期连续优势树种，Schima superba Gardn。et Champ , 以及典型的后继优势树种Cryptocarya concinna Hance以100%全光（FL）和30% FL（低光，LL）为材料，探讨亚热带森林不同演替阶段树种对不同光环境的响应。转录组测序用于分析不同光照环境下生长和光保护相关基因的表达变化。的嫩叶木荷积累了更多的丙二醛（MDA）和超氧自由基（⁠| $ {\ mathrm {Ø}} _ 2 ^ {{{} ^ {\子弹}} ^ { - }} $ |⁠）LL下. LL下还发现幼叶激素（生长素、细胞分裂素、赤霉素）含量较低，成熟叶光合能力较弱，相关基因表达显着下调，导致总生物量LL 下的S. superba低于 FL 下的S. superba。C. concinna幼叶的MDA 和|${\mathrm{O}}_2^{{{}^{\bullet}}^{-}}$|⁠ 较少，LL 下的激素含量高于那些在 FL 下。在对比光环境下，成熟叶片之间的光合能力没有显着差异。虽然LL下C. concinna的生物量低于 FL 下的生物量，但LL 下C. concinna的高度高于 FL 下的C. concinna在两种光照环境下都能很好地生长。我们在生理、分子和转录组水平上描述光适应的结果对于完整理解演替机制很重要。